5830 EVERGREEN WAY 2016-01-01 MF Import

i � IHousing Hope 5hort Plat D�ainage Analysis IPage 4 . , IA catch basin on the south side of the property in Basin A will be installed to collxt tunoff from off-site areas draining into Basin A. 'Ilie flow will then be directed to the storm dreinage system in Basin A through an 8-inch pipe. Lot 4, located in Basin B, includes rehabilitation of the euisting building into a commercial facility �_ for use as offices; conswction of a commercial building for rontel aparunent�rnits,daycare centa and offices; paving for a parking lot and access driveway; landscaping aroun3 buildings; and �_ conswction of a children's playground and improverunts to foofpefhs. Foodng drnins and roo€ ' downspouts will collect runoff and drain to catch basins. Runoff from the exposed portions of the (_ parking lot will drain as sheet Flow to a Type II Catch Basin for grit removal. Runoff from the exposed delivery access driveway x�ill be directed to a Type I Catch Basin for grit�emoval. The Idrainage in the catch basins will then be directed to a 15 foo;by 50 foot open widerground reinforced concnete detention vault located on die north side of Lot 3. One foot of dead water I storage above 1 S" of soil will be included in die wet vault to allow for sediment remaval and water treatment. lOutflow from both detention systems will be coi�trolled in restrictor menholes to match the existing 10-year and 100-year stonn events and 1/2 of the 2-year stoRn event. Outflow will then be routed Ito Pigeon Creek as channel flow in underground cuiverts. Two foot b:idges spanning between 18 and 20 feet are also proposed for consuuction over Pigeon Creek. These four-foot wide bridges will have a minimum of at least one foot clearance from the � high water mark in the creek (see calculations in Appendix). � Phasing Sequence for Constructic�n 71ie proposed pinject will be constructed in phases. � , , M1 The first phase,expected to begin in the Fall of 1996, will include installation of individual sto�m f drainage outfalls for both sub-basins. The two pipes (located on the west side of the property) to � be consnvcted will be put in place prirr to consuvction of the wet vaults. I I . I